1. Field of the Invention
The present invention relates to a water base ink set for ink-jet recording to perform the color ink-jet recording.
2. Description of the Related Art
The ink-jet recording method adopts a variety of ink discharge methods including, for example, the electrostatic attraction method, the method in which mechanical vibration or displacement is applied to the ink by using a piezoelectric element, and the method in which bubbles are generated by heating the ink to utilize the pressure generated thereby. Ink droplets are formed by means of the discharge method as described above, and all or a part of the droplets are adhered to a recording objective to perform the recording.
Those hitherto known and used as the ink to be employed for the ink-jet recording method as described above include those in which a variety of water-soluble dyes or pigments are dissolved or dispersed in liquid media each comprising water or a combination of water and water-soluble organic solvent.
As the printer based on the ink-jet system comes into widespread use, the printer is used to record picture images or the like, for example, in ordinary homes. In such circumstances, coloring agents, which enhance the light resistance of the ink, are used in order to hardly cause the changes of colors even after storage for a long term.
However, the conventional technique has involved the following problem.
In the conventional technique, attention has been paid to enhance the light resistance of each of the colors. The light resistance has differed among the respective colors, and the color balance among the color has not been maintained after the fading. For example, the time-dependent changes of colors, which are caused by the light after recording an image of a red apple, advance as follows. The red color is formed by the yellow ink and the magenta ink. When the light resistance of the yellow ink is extremely inferior to the light resistance of the magenta ink, only the color of magenta remains on the recording material. The image of the apple, which has been red, is changed into an apple of magenta color, making an unnatural impression.
The present invention has been made in order to solve the conventional problem as described above, an object of which is to provide a water base ink set for ink-jet recording with which the color balance is adjusted by uniformalizing the light resistances of respective color inks, and the color balance is also maintained for an image after the fading.
According to the present invention, there is provided an ink set for ink-jet recording comprising:
a yellow ink, a magenta ink, and a cyan ink, wherein:
changes of colors xcex94EY, xcex94EM, xcex94EC of the yellow ink, the magenta ink, and the cyan ink satisfy the following relationship when the yellow ink, the magenta ink, and the cyan ink are deposited on regular paper, followed by being irradiated with light having a wavelength of 300 nm to 400 nm and an illuminance of 100 W/m2 for 30 hours by using a xenon lamp:
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The ink set may be in a form of an ink cartridge having compartments which accommodate the yellow ink, the magenta ink, and the cyan ink respectively.
The water base ink set for ink-jet recording of the present invention comprises at least the yellow ink, the magenta ink, and the cyan ink.
Each of the yellow ink, the magenta ink, and the cyan ink includes, for example, those composed of water, a moistening agent, and a coloring agent.
The water is not specifically limited. However, it is preferable to use water having high purity such as ion exchange water and distilled water excluding, for example, tap water. The blending amount of the water may be determined depending on the type and the composition of the moistening agent and the coloring agent or the characteristics of the desired ink. However, in general, it is preferable that the blending amount is 10 to 98% by weight with respect to the total weight of the ink. If the blending amount is less than 10% by weight, or if the blending amount exceeds 98% by weight, then it is difficult that the viscosity of the ink in the ordinary state is maintained to be a viscosity at which the ink can be normally jetted. The blending amount is more preferably 30 to 97% by weight, and much more preferably 40 to 95% by weight.
The moistening agent is not specifically limited. For example, it is possible to use glycol ethers or the like represented by compounds based on ethylene glycol and propylene glycol and alkyl ethers thereof.
The moistening agent based on ethylene glycol includes, for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, ethylene glycol-n-methyl ether, ethylene glycol-n-ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-n-butyl ether, ethylene glycol-n-isobutyl ether, diethylene glycol-n-methyl ether, diethylene glycol-n-ethyl ether, diethylene glycol-n-propyl ether, diethylene glycol-n-butyl ether, diethylene glycol-n-isobutyl ether, triethylene glycol-n-methyl ether, triethylene glycol-n-ethyl ether, triethylene glycol-n-propyl ether, triethylene glycol-n-butyl ether, and triethylene glycol-n-isobutyl ether.
The moistening agent based on propylene glycol includes, for example, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, propylene glycol-n-methyl ether, propylene glycol-n-ethyl ether, propylene glycol-n-propyl ether, propylene glycol-n-isopropyl ether, propylene glycol-n-butyl ether, dipropylene glycol-n-methyl ether, dipropylene glycol-n-ethyl ether, dipropylene glycol-n-propyl ether, dipropylene glycol-n-isopropyl ether, dipropylene glycol-n-butyl ether, tripropylene glycol-n-methyl ether, tripropylene glycol-n-ethyl ether, tripropylene glycol-n-propyl ether, tripropylene glycol-n-isopropyl ether, and tripropylene glycol-n-butyl ether.
Other than the above, the moistening agent includes, for example, polyhydric alcohol such as 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerol, 1,2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3-butanetriol, and pentanetriol; nitrogen-containing heterocyclic compound such as N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, and xcex5-caprolactam; amide such as formamide, N-methylformamide, and N,N-dimethylformamide; amine such as monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, and triethylamine; and sulfur-containing compound such as dimethylsulfoxide, sulfolane, and thiodiethanol.
Each of the moistening agents as described above may be used singly, or two or more of them may be used in combination.
In general, the blending amount of the moistening agent as described above is preferably 1 to 80% by weight with respect to the total weight of the ink. If the blending amount is less than 1% by weight, it is impossible to obtain the effect of addition of the moistening agent. If the blending amount exceeds 80% by weight, for example, problems arise in some cases such that the viscosity of the ink is unnecessarily increased to make it impossible to discharge the ink, or the ink is dried extremely slowly on the recording paper. More preferably, the blending amount is 3 to 60% by weight, and much more preferably 5 to 50% by weight.
Those usable as the coloring agent include, for example, water-soluble dyes represented by direct dye, acidic dye, basic dye, and reactive dye.
Further, for example, those preferably used as the water-soluble dye include those classified, for example, into azo dye, metal complex salt dye, naphthol dye, anthraquinone dye, indigo dye, carbonium dye, quinoneimine dye, xanthene dye, aniline dye, quinoline dye, nitro dye, nitroso dye, benzoquinone dye, naphthoquinone dye, phthalocyanine dye, and metal phthalocyanine dye.
It is preferable that the ink to be used for the ink-jet recording system satisfies required performance such as vividness, water solubility, stability, light resistance, and other required performance. Therefore, the coloring agent to be used is selected from those which satisfy the requirements as described above.
The direct dye includes, for example, C. I. Direct Yellow 12, 24, 26, 27, 28, 33, 39, 58, 86, 98, 100, 132, 142; C. I. Direct Orange 34, 39, 44, 46, 60; C. I. Direct Red 4, 17, 28, 37, 63, 75, 79, 80, 83, 99, 220, 224, 227; C. I. Direct Violet 47, 48, 51, 90, 94; C. I. Direct Brown 109; C. I. Direct Green 59; and C. I. Direct Blue 1, 6, 8, 15, 25, 22, 25, 71, 76, 80, 86, 90, 106, 108, 123, 163, 165, 199, 226.
The acidic dye includes, for example, C. I. Acid Yellow 3, 11, 17, 19, 23, 25, 29, 38, 42, 49, 59, 61, 71, 72; C. I. Acid Orange 7, 19; C. I. Acid Red 1, 6, 8, 17, 32, 35, 37, 42, 51, 52, 57, 80, 85, 87, 92, 94, 115, 119, 131, 133, 134, 154, 181, 186, 249, 254, 256, 289, 315, 317; C. I. Acid Violet 10, 34, 49, 75; and C. I. Acid Blue 9, 22, 29, 40, 59, 62, 93, 102, 104, 113, 117, 120, 167, 175, 183, 229, 234.
The basic dye includes, for example, C. I. Basic Red 1, 2, 9, 12, 13, 14, 37; C. I. Basic Violet 7, 14, 27; and C. I. Basic Blue 1, 3, 5, 7, 9, 24, 25, 26, 28, 29.
The reactive dye includes, for example, C. I. Reactive Yellow 2; C. I. Reactive Red 4, 23, 24, 31, 56; and C. I. Reactive Blue 7, 13.
It is preferable that the coloring agent is blended in an amount of 0.1 to 15% by weight with respect to the total weight of the ink. If the blending amount is less than 0.1% by weight, then the speed of fading of the ink is suddenly quickened on the recording paper, and the color balance is not maintained in some cases. On the other hand, if the blending amount exceeds 15% by weight, a problem sometimes arises such that the coloring agent is deposited in the ink. The blending amount is more preferably 0.3 to 10% by weight, and much more preferably 0.5 to 5.0% by weight.
The coloring agent, which has been contained in the conventional recording ink, has been selected and used so that the light resistance is excellent as far as possible for each of the colors. However, in general, the coloring agents of yellow and cyan are excellent in light resistance, and the coloring agent of magenta is inferior in light resistance. Therefore, the light resistance has greatly differed among the yellow ink, the magenta ink, and the cyan ink. For this reason, when an image is recorded on the regular paper, then the color balance among the colors has not been maintained after the fading, and the image has been changed into an unnatural image in which the yellow and blue colors are intense and the red color is exhausted or worn out.
Those in which the light resistances on the recording paper are uniform for the yellow ink, the magenta ink, and the cyan ink are preferably used for the coloring agents which are contained in the inks for constructing the water base ink set for ink-jet recording of the present invention. That is, the coloring agents are selected so that the relationships of |xcex94EYxe2x88x92xcex94EM|xe2x89xa65, |xcex94EMxe2x88x92xcex94EC|xe2x89xa65, |xcex94ECxe2x88x92xcex94EY|xe2x89xa65 are established. Preferably, the coloring agents are selected so that 5xe2x89xa6xcex94EYxe2x89xa610, 5xe2x89xa6xcex94EMxe2x89xa610, 5xe2x89xa6xcex94ECxe2x89xa610 are satisfied.
In general, the light resistance of the coloring agent of magenta is inferior. Therefore, in the present invention, the coloring agents having good light resistances among the coloring agents of yellow and cyan can be used by mixing them with the coloring agents having low light resistances in order to uniformalize the light resistances. When the light resistances are made uniform among the yellow ink, the magenta ink, and the cyan ink, an image recorded on the regular paper is maintained with good color balance even after the fading.
originally, the direct dye as described above is the anionic dye for dyeing cellulose fibers. The direct dye is classified, for example, into those of azo, stilbene, thiazole, dioxazine, and phthalocyanine depending on the chemical structure. However, almost all of the direct dyes are azo dyes. Especially, those having excellent light resistances are phthalocyanine and dioxazine dyes.
The acidic dye is utilized to dye polyamide-based fibers such as wool, nylon, and silk. The acidic dye is classified, for example, into those of azo, anthraquinone, triphenylmethane, and xanthene depending on the chemical structure. The light resistance of the anthraquinone-based dye is good. However, the light resistances of the triphenylmethane-based and xanthene-based dyes are inferior.
The light resistance of the basic dye is generally inferior.
The reactive dye has, in the dye molecule, a reactive group to react with a hydroxyl group or an amino group. The reactive dye dyes the fiber by reacting with the hydroxyl group or the amino group in the fiber to form covalent bond. The reactive dye is dominantly used for cellulose, and it has good light resistance.
According to the fact described above, in general, the direct dye and the reactive dye have relatively good light resistances, and the acidic dye and the basic dye have relatively inferior light resistances. In the present invention, the light resistance of the color ink can be controlled by combining those having good light resistances and those having inferior light resistances.
Additionally, each of the inks for constructing the water base ink set for ink-jet recording of the present invention may optionally contain, for example, hitherto known various types of dispersing agents, surfactants, viscosity-adjusting agents, surface tension-adjusting agents, pH-adjusting agents, antiseptic agents, and fungicides. Inks of other colors such as a black ink may be contained in the water base ink set for ink-jet recording of the present invention.
The problem involved in the conventional technique is sufficiently solved in the water base ink set for ink-jet recording of the present invention obtained as described above. It is possible to provide the vivid color recording over a long term.